North Korea has told its key ally, China, that it is prepared to stage one or even two more nuclear tests this year in an effort to force the United States into diplomatic talks, said a source with direct knowledge of the message.

Further tests could also be accompanied this year by another rocket launch, said the source, who has direct access to the top levels of government in both Beijing and Pyongyang.

North Korea conducted its third nuclear test on Tuesday, drawing global condemnation and a stern warning from the United States that it was a threat and a provocation.

“It’s all ready. A fourth and fifth nuclear test and a rocket launch could be conducted soon, possibly this year,” the source said, adding that the fourth nuclear test would be much larger than the third, at an equivalent of 10 kilotons of TNT.